With the developing of transport network, the network topology is more and more complicated and the service volume is larger and larger. To meet the requirement of scheduling granularities of different services, ASON (Automatic Switch Optical Network) supports several switching capabilities and service scheduling of different rates under each switching capability. Multilayer network is constituted by the support for the various switching capabilities and different rates under each switching capability, such as the multilayer networks of MPLS (Multiprotocol Label Switching) and GMPLS (Generalized Multiprotocol Label Switching).
A Label Switched Path (LSP) is established on a boarder node of a layer. If the LSP is flooded as a Traffic Engineering (TE) link of the higher layer, the LSP is referred to as a FA (Forwarding Adjacency) LSP, and the TE link is referred to as FA (Forwarding Adjacency). Routing adjacency relationship does not exist between end points of FA, but a signaling adjacency relationship exists therein.
The FA LSP may be automatically established or manually established.
The manual way of establishing the FA LSP means to plan and configure well in advance. The most deficiency of the way is that it is not flexible enough and the efficiency of the whole network is not optimal.
To establish automatically, the FA may use three models: a Path Compute Element-Virtual Network Manager (PCE-VNTM) cooperative model, Network Manager System-Virtual Network Manager (NMS-VNTM) cooperative model or higher-layer signaling triggering model. The first two models both introduce VNTM, which may lead to the difficulty of layout, the increasing of content that needs to be coordinated and interchanged, the increasing of the time for LSP establishing and instability.
When the higher-layer signaling triggering model is used, it is difficult for the beginning node on the boarder of the layer to learn the beginning node and the end node in the FA LSP to initiate an establishment of the LSP to the end node in the FA LSP. There is no related resolution now.